Adaptively modifying pre-read operations within a rotating media storage device

Abstract

A rotating media storage device (RMSD) that adaptively modifies pre-read operations is disclosed. The RMSD schedules a pre-read data segment on a second track of disk, commands a movable head to seek to the second track, and if an on-track condition is not met for the scheduled pre-read data segment, modifies the pre-read operation. In one example, modifying the pre-read operation includes canceling the pre-read operation and then performing a read data operation.

1. A rotating media storage device (RMSD) connectable to a host computer, the RMSD comprising:
 a disk including at least a first track and a second track; 
 a moveable head; 
 a cache memory to store data segments from the disk that have been previously read; and 
 a microprocessor for controlling operations in the RMSD including seek operations and read operations that include pre-read operations to read pre-read data, read data operations for reading read data, and post-read operations to read post-read data, wherein the reading of the pre-read data is adaptively modified such that a remaining portion of data segments of the pre-read data is read and the read data and the post-read data are read, within one disk drive revolution, the microprocessor under the control of a program to: 
 a. schedule a forecasted pre-read data portion on the second track, wherein the scheduled pre-read data portion includes a plurality of data segments; 
 b. command the moveable head to seek to the second track; 
 c. determine if an on-track condition is physically met for the scheduled pre-read data portion based upon servo position information from a servo controller, and if so, perform the pre-read operation for the scheduled pre-read data portion; and 
 d. determine if the on-track condition cannot be met for the scheduled pre-read data portion based upon servo position information from a servo controller, and if not, adaptively modify the scheduled pre-read data portion based on a calculation of a remaining portion of the scheduled pre-read data portion to be read based upon servo position information from the servo controller that determines a physical component that includes a number of data segments that are readable from the scheduled pre-read data portion and based upon a caching component associated with determining whether, based upon rules of a read caching algorithm that determine if coherency factors are met, the read caching algorithm would support reading the remaining portion of the pre-read data, wherein if both the physical component and the caching component are satisfied, the remaining portion of data segments of the scheduled pre-read data portion is read and the read data and the post-read data are read, within one disk drive revolution. 
 
     
     
       2. The RMSD of  claim 1 , wherein, if the physical component or the caching component is not satisfied, adaptively modifying the scheduled pre-read data portion includes canceling the pre-read operation and then performing the read data operation to read the read data. 
     
     
       3. The RMSD of  claim 1 , wherein, the physical component includes a pre-determined minimum number of data segments that are required to be read from the scheduled pre-read data portion. 
     
     
       4. In a rotating media storage device (RMSD) connectable to a host computer, the RMSD having a disk including at least a first track and a second track, a moveable head, a servo controller, a cache memory to store data segments from the disk that have been previously read and a microprocessor for controlling operations in the RMSD including seek operations and read operations that include pre-read operations to read pre-read data, read data operations for reading read data, and post-read operations to read post-read data, wherein the reading of the pre-read data is adaptively modified such that a remaining portion of data segments of the pre-read data is read and the read data and the post-read data are read, within one disk drive revolution, a method of efficiently switching between a read operation on the first track and a read operation on the second track, the method comprising the steps of:
 a. scheduling a forecasted pre-read data portion on the second track, wherein the scheduled pre-read data portion includes a plurality of data segments; 
 b. commanding the moveable head to seek to the second track; 
 c. determining if an on-track condition is physically met for the scheduled pre-read data portion based upon servo position information from the servo controller, and if so, performing the pre-read operation for the scheduled pre-read data portion; and 
 d. determining if the on-track condition cannot be met for the scheduled pre-read data portion based upon servo position information from the servo controller, and if not, adaptively modifying the scheduled pre-read data portion based on a calculation of a remaining portion of the scheduled pre-read data portion to be read based upon servo position information from the servo controller that determines a physical component that includes a number of data segments that are readable from the scheduled pre-read data portion and based upon a caching component associated with determining whether, based upon rules of a read caching algorithm that determine if coherency factors are met, the read caching algorithm would support reading the remaining portion of the pre-read data, wherein if both the physical component and the caching component are satisfied, the remaining portion of data segments of the scheduled pre-read data portion is read and the read data and the post-read data are read, within one disk drive revolution. 
 
     
     
       5. The method of  claim 4 , wherein, if the physical component or the caching component is not satisfied, adaptively modifying the scheduled pre-read data portion includes canceling the pre-read operation and then performing the read data operation to read the read data. 
     
     
       6. The method of  claim 4 , wherein, the physical component includes a pre-determined minimum number of data segments that are required to be read from the scheduled pre-read data portion. 
     
     
       7. A computer system comprising a host computer and a rotating media storage device (RMSD), the RMSD further comprising:
 a disk including at least a first track and a second track; 
 a moveable head; 
 a cache memory to store data segments from the disk that have been previously read; and 
 a microprocessor for controlling operations in the RMSD including seek operations and read operations that include pre-read operations to read pre-read data, read data operations for reading read data, and post-read operations to read post-read data, wherein the reading of the pre-read data is adaptively modified such that a remaining portion of data segments of the pre-read data is read and the read data and the post-read data are read, within one disk drive revolution, the microprocessor under the control of a program to: 
 a. schedule a forecasted pre-read data portion on the second track, wherein the scheduled pre-read data portion includes a plurality of data segments; 
 b. command the moveable head to seek to the second track; 
 c. determine if an on-track condition is physically met for the scheduled pre-read data portion based upon servo position information from a servo controller, and if so, perform the pre-read operation for the scheduled pre-read data portion; and 
 d. determine if the on-track condition cannot be met for the scheduled pre-read data portion based upon servo position information from a servo controller, and if not, adaptively modify the scheduled pre-read data portion based on a calculation of a remaining portion of the scheduled pre-read data portion to be read based upon servo position information from the servo controller that determines a physical component that includes a number of data segments that are readable from the scheduled pre-read data portion and based upon a caching component associated with determining whether, based upon rules of a read caching algorithm that determine if coherency factors are met, the read caching algorithm would support reading the remaining portion of the pre-read data, wherein if both the physical component and the caching component are satisfied, the remaining portion of data segments of the scheduled pre-read data portion is read and the read data and the post-read data are read, within one disk drive revolution. 
 
     
     
       8. The RMSD of  claim 7 , wherein, if the physical component or the caching component is not satisfied, adaptively modifying the scheduled pre-read data portion includes canceling the pre-read operation and then performing the read data operation to read the read data. 
     
     
       9. The RMSD of  claim 1 , wherein, the physical component includes a pre-determined minimum number of data segments that are required to be read from the scheduled pre-read data portion.